Method of treating wool to prevent felting during wet processing



Patented Feb. 13, 1951 METHOD OF TREATING 'WOOL TO PREVENT FELTING DURING WET PROCESSING Malcolm J. Reider, 'Shillington, Pa., assignor to Geo. W. Bollman & 00., Inc., Adamstown, ,Pa., a corporation of Pennsylvania No Drawing. Application October 25, 1949,-

Serial No. 123,530

4 Claims.

., This invention relates to a method for shrink proofing wool, more particularly by a treatment for avoidance of milling or felting shrinkage normally occurring when wool is scoured, washed, or otherwise wet processed.

Wool fibres, as is known, possess a well defined surface scale structure which imparts to the wool certain frictional properties, more friction being developed by. rubbing the fibre in adirection from its tip to its root than is developed by rubbing the fibre in the opposite direction.

This differential frictional effect, which occurs in the washing or'scouring of wool fabrics, causes the mass, ofwool, fibres .of the fabrics to migrate which results in felting or millin shrinkage of such fabrics.

Now in ac cordan'ce with th-is invention broadly, it has-been found that felting or milling shrinkvgage of masses of wool fibres, as, for example, in

wool fabrics, will be greatly reduced by adsorb- ,ing on the surfaces of the wool fibres a finely edivided material of such size as to clog the surface scales of the fibres, thus largely eliminating the differential frictional effect occurring in washing or scouring and consequently the ability 'of the fibresto'felt.

More particularly, amass of wool fibres, as a wool fabric, may be treated according to this invention for the clogging of the surface scales thereof with finely divided material, and then washed or scoured with water containing a deter- I gent, or the deter-gentmay be added to the Wool with the finely divided material and the wool then washed in plain water.

In treating wool fibres in accordance with this invention, the finely divided material may be applied to the fibres through the medium of a vehi cle or may be formed in situ.

The finely divided material, whether applied to the wool through the medium of a vehicle or formed in situ, may be of any composition so long as it is water-insoluble and does not change the physical or chemical structure of the wool and is of a size to collect in and under the scale angles of the surface scales of the fibre. Optimum results will be obtained using finely divided material of a size from a fraction of a micron up to not largely greater than one micron and in amount up to not greatly in excess of 20% by Weight, for example, within about the range 5%-20% by Weight.

When the finely divided material used carries a negative charge, the treatment of the wool fibres therewith must be on the acid side of the isoelectric point of the wool and for the optimum 2 should be in the range of pH 2.0 topH 3.5. Then, in washing wool so treated, a nonionic or cationic detergent is usedso that the cleansing action will .be effective under acid conditions. 'On the other hand if the finely divided material carries a positive charge, the treatmentof the wool therewith must be on the alkaline side of the isoelecme point of the wool, preferably in the range-of pH 8.5 to pH 11.0 when the wool fibres will then possess a negative charge. In washing the Wool so treated, a nonionic or anionic detergent must be used for effective cleansing under these conditions. I I

When it is desired to remove the finely "divided materials after the wool fibres are Washed, and in many cases they may be left in place, :such will be accomplished by rinsing the fibres under reverse (alkaline or acid) conditions-to reverse the polarity of the wool overthat at which the finely divided materials were applied.

As specifically illustrative of finely divided materials which may be used incarrying out this invention, the following may be mentioned as carrying a negative charge:

. Bentonite clays I Fullers earth or diatomaceous earth Finely divided pigments such as T102 Silica Carborundum Pumicepowder Silicic acid powder Precipitated compounds such as barium Sui-- fate, calcium sulfateflead chromate, etc.

and cationic substances such as various of the well known ion exchange resins will be illustrative of materials carrying a positive charge.

In treating wool fibres with finely divided materials carrying a negative charge, the material will be suspended in water containing an acid such as acetic, formic, and the like, or a mineral acid such as sulfuric, hydrochloric and the like in amount to give to the suspension a pH below pH 5.0, preferably within about the range pH 2.0-3.5, and the suspension applied to the Wool. When the material used carries a charge, the suspension thereof wil1 be given a pH on the alkaline side, preferably within about the range pH 8.5-11.0, with use of a base, as, for example, sodium hydroxide, ammonia, or the like.

As specifically illustrative of procedure according to this invention, for example, woolen socks are treated with a suspension, comprising 10% by Weight of the socks of finely divided titanium dioxide, of a particle size of minus one micron dispersed in water in amount to saturate the socks andjhaving a pH of about pH 3.0, obtained through the use of acetic or sulfuric acid.. The titanium dioxide particles will, due to their pposite polarity to that of the wool, be attracted to the wool fibres and will be adsorbed thereby and will effectively clog the surface scales of the fibres and reduce their tendency to felt under the mechanical action to which they are subjected on washing in hot water containin a cationic or non-ionic detergent.

As has been indicated, the detergent may be applied tothe socks by including it in the aqueous suspension of the titanium dioxide, and the socks then washed in plain water.

As illustrative of procedure involving the formation of the finely divided material in situ, for

4 2. In the wet processing of wool, the improvement which comprises forming a deposit of finely divided material between the scales of the wool fibres by treating the wool fibres with an aqueous suspension of a water-insoluble finely divided 'material, inert to the wool and carrying a negative charge, at a pH less than pH 4.0, whereby in the presence of such finely divided material felting of the Wool is prevented during wet-processing.

3. In the wet processing of wool, the improvement which comprises forming a deposit of finely divided material between the scales of the wool fibres by treating the wool fibres with an aque ous suspension of a water-insoluble finely divided material, inert to the wool and carrying a. mega example," the wool socks in water containing, for

example, sulfuric acid, are treated with barium chloride in solution. Barium sulfate will precipitate and will be adsorbed by the wool fibres. Such reactions are, of course, well known.

When the socks, the wool fibres carrying the What is claimed is: 1. In the wet processing of wool, the improvement which comprises forming a deposit of finely divided material between the scales of the wool fibres by treating the wool fibres with an aqueous suspension of a water-insoluble finely divided material inert to the woolat a pH differing from the isoelectric point of the wool, the said finely divided material being one having a negative charge when the wool is processed on the acid side of said isoelectric point and being one having a positive charge when the wool is processed on the alkaline side of said isoelectric point, whereby in the presence of such finely divided material felting of the wool is prevented during wet-processing.

tive charge, at a pH within about the range pH 2.0-4.0, whereby in the presence of such finely divided material felting of the wool is prevented during wet-processing. I

4. In the wet processing of Wool, the improvement which comprises forming a deposit of finely divided material between the scales of the wool fibres by treating the Wool fibres with an aqueous suspension of a water-insoluble finely divided material, inert to the wool and carrying a positive charge, at a pH in excess of pH 8.5, whereby in the presence of such finely divided material felting of the wool is prevented during wet-processing.

' MALCOLM J. REIDER.

REFERENCES CITED The following references are of record in his file of this patent:

UNITED STATES PATENTS Number Name Date 1 1,515,647 Airheart Nov. 18, 1924 1,608,418 Payne Nov. 23, 1926 1,732,729 Phair Oct. 22, 1929 1,947,024 Slagle Feb. 13, 1934 2,438,328 Speakman Mar. 23, 1948 OTHER REFERENCES Dunbar, Modern Developments in Textile Chemicals, Journal Soc. Dyers and Colourists, vol. 50, Oct. 1934, pages 309-815, pp. 314, 315 esp.

pertinent.

Schofield, The Wet Processes of the Wool In dustries, Netherwood, Dalton & Co., Ltd., Folly Hall, Huddersfield, 1924, pages 106-108. 

1. IN THE WET PROCESSING OF WOOL, THE IMPROVEMENT WHICH COMPRISES FORMING A DEPOSIT OF FINELY DIVIDED MATERIAL BETWEEN THE SCALES OF THE WOOL FIBRES BY TREATING THE WOOL FIBRES WITH AN AQUEOUS SUSPENSION OF A WATER-INSOLUBLE FINELY DIVIDED MATERIAL INERT TO THE WOOL AT A PH DIFFERING FROM THE ISOELECTRIC POINT OF THE WOOL, THE SAID FINELY DIVIDED MATERIAL BEING ONE HAVING A NEGATIVE (-) CHARGE WHEN THE WOOL IS PROCESSED DON THE ACID SIDE OF SAID ISOELECTRIC POINT AND BEING ONE HAVING A POSITIVE (+) CHARGE WHEN THE WOOL IS PROCESSED ON THE ALKALINE SIDE OF SAID ISOELECTRIC POINT, WHEREBY IN THE PRESENCE OF SUCH FINELY DIVIDED MATERIAL FELTING OF THE WOOL IS PREVENTED DURING WET-PROCESSING. 